The present invention relates to a device for farming benthic organisms such as bivalves, and particularly relates to a device used for farming benthic organisms living in an environment exposed to tides, such as venerupis philippinarum, meretrix lusoria, and corbiculidae.
Bivalves, of which venerupis philippinarum, meretrix lusoria, corbiculidae, and the like are representative, are typical popular Japanese seafood and are sources of marine protein that can be inexpensively taken by the masses. However, currently, due to a decrease of sand beaches, tidal flats, and the like, due to water pollution of the ocean regions, coastal bank reinforcement, and the like, reserves and catches have declined sharply. Currently, to preserve the reserves and catches for bivalves, farming is being done in various regions, and many of the farming methods artificially seed spats on the sea coast and then cultivate these in a natural environment. However, these conventional farming methods are influenced by changes in the ocean region environment, have expensive production costs, and cannot provide the market with a stable supply.
Meanwhile, looking at actions affecting the bivalve environment, in terms of methods for feeding bivalves, minute phytoplankton, which floats suspended in the sea water, and detritus, which is broken pieces of the same, are filtered by way of gills, and in terms of the filtration capacity thereof, venerupis philippinarum with a shell length of approximately 3 cm filters approximately 3 liters of seawater per day, contributing to purification of the ocean region, in which eutrophication materials are removed.
In terms of broadly classifying conventional technology proposed for shellfish farming devices, this can be divided into mariculture and land-based farming. Because, for farming devices in the ocean, spats are cultivated by enclosing a plate or the like to which spats are attached with a net and lowering into seawater, it has the merit of easily providing an environment that is comparatively close to the natural habitat conditions (see JP-3913669-B and Patent Document 2 JP-3979746-B). However, the selling price for bivalves is low, and production costs are an issue, thus bivalves remain in a low position as farmed seafood. In particular, at present, costs are a problem in terms of achieving land-based farming, and thus this has not been substantially implemented.
For example, in JP-3493357-B, farming facilities for abalone on land are described. In terms of these farming facilities for abalone, an abalone breeding tank is arranged in multiple levels, and the abalone breeding tank is provided with a water supply pipe that supplies seawater and an overflow pipe, furthermore, an air supply pipe and a feed supply area are also fixed in the breeding tank. Furthermore, in addition to causing seawater to flow into the water supply pipe with a pump, by lowering the overflow pipe, the seawater flows to the lower level water tank, so that the flow of seawater is promoted. Furthermore, for the air supply pipe, air is provided with a blower, and compressed air is sprayed out as froth. Thus, dissolved oxygen is supplied.